[vlc] Re: Problems with Multicast Traffic

[Joel Jaeggli]

Rémi Denis-Courmont wrote:
> On Thu, 24 May 2007 09:41:35 +0200, "Arturo J. Gómez Villegas"
> <ajgv354 at tid.es> wrote:
>> I was already able to route multicast traffic through HOTSPOT. I'm
>> proving with mp3 and the results are not good. Probably the bottleneck
>> is the access point, but I need that it's heard well.
> 
> There are several problems with multicast over 802.11, such as
> throttling and inefficiency of error correction (there is no
> retransmission for multicast as for unicast).

The biggest problem is generally that the multicast rate is pegged at
the slowest rate the ap can support so typically 1Mb/s if you can alter
that you can achieve dramatically better performance though packet-loss
to do interference/collisions is still an issue.

setting the multicast rate on the ap to 5.5 or 6 (g only) or higher will
help. ;)

> In practice, multicast over WiFi is only usable for very small
> bandwidth usages, such as discovery protocols.
> 
> As such to stream over WiFi, you should always use unicast, even
> if this means wasted bandwidth when there are more than one
> client associated with a given AP.
> 
>> For videos I'm trying to reduce the bit-rate, but not with himself
>> nothing. There is some form to improve this situation?
> 
> Some AP might allow tweaking some settings, but you should refer to
> the AP documentation. Unlikely to solve the problem anyway.
> 

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